Sunday, May 19, 2013

Kayak Review - Jackson Karma part 2

I had another day in the Jackson Karma on some harder whitewater and have some more thoughts to add (if you missed my first impressions, that post is here, and an update after a year with the boat is here). This is partly going to be about the Karma but also about hull shapes and paddling in general. In my earlier post I referred to the differences between planing hulls and displacement hulls and how each requires a different style of paddling. I want to get a little more specific with that.

Jackson Karma
First, an acknowledgement. Most kayaks don't have pure hulls. They're not entirely flat or entirely rounded. Even displacement hulls can have edges and some planing hulls look rounder than others. The lines keep getting more blurred but there's still a difference and even if you can't see it you can feel it. It's all about the interaction of the boat with the water. We kayakers just make it easier on ourselves but saying it's a planing hull. We're really describing how the boat paddles more than the exact shape of the hull. It's the performance that we care about.

Karma front view
The term displacement comes from the fact that boats displace water and the buoyant force from that fact is what holds the boat up. All boat at rest are displacement boats. But when you start moving a boat through the water things change. If the hull is flat and there's some bow rocker, then there starts to be a lifting force from the movement of the boat over the water. If the boat moves fast enough then that lift becomes the main force that is holding the boat up - in that case the hull is skimming over the surface and pushing less water.

The speeds required to get a boat to plane are virtually impossible to achieve though paddling alone. Full planing requires the assistance of gravity and that is normally found on a wave. And that is exactly where planing hulls shine - in playboats. When a boat planes it has less resistance, resulting in faster speeds and easier maneuvering. That's surfing.

But this doesn't really happen when creeking. So why would you want a planing hull creek boat? Because that planing nature of the hull can create different characteristics even if full planing speeds are not achieved. (not to mention that people who use playboats a lot are more used to the feel)

Karma side view
All things being equal, when boats are operating in displacement mode a round hull is faster over the long haul than a flat one (check out the bottom of a sprint kayak if you get the chance). But acceleration is a different beast. Flat hulls often are quicker to get up to speed since they ride up over the water without pushing through it as much. Acceleration can be a more important factor than cruising speed on the river.

Another benefit of a flat hull that isn't buried as deep in the water is maneuverability. They can spin quicker. Again, that can be a great advantage on the river. Overall, planing hulls often feel quicker (as opposed to faster). That's makes them good for reacting. The downfall to this freedom is the fact that when the water exerts force on the boat it is more likely to turn. Rounder hulls tend to hold their line better and resist currents pushing them about.

Donnells Run
So let's get back to the Karma. The Karma is a planing hull creeker. I normally paddle the displacement hull Villain. At the end of my last Karma review I stated that I was going to stick with the Villain. That was before I cracked the hull of my Villain (a post on repairing cross-linked plastic boats is now up here). So I took a demo Karma out on a good class IV-V run and learned a bit more about how it paddles.

The first thing that I really noticed was that my timing was off. The river started rather wide and full of boulders. Lots of boofs and rock dodging. The ease of turning the Karma was great and it auto-boofs over most anything. But I was turning and reaching eddies faster than I expected. Same on the boofs - the last couple of strokes would accelerate me faster than expected and I would be late on my final stroke (1:24 in video). I had to realize that I could do less work myself and the boat would make up for it. That's a good thing but something that takes time to get used to.
Villain on top; Karma bottom
Both boats bow forward

One of the other things that I was worried about with a flat hull was the landing off of said boofs. Flat hits can be hard on the body and displacement hulls definitely land softer. While I didn't launch off anything that high, I found the Karma never seemed to hit hard. The Jackson folks claim that the design of a narrow bow and lots of rocker allow the boat the accelerate through landings. The picture to the left shows the narrower/flatter hull shape of the Karma (bottom) compared to the Villain (top). I'm not entirely convinced that it will hold true if you manage to catch air and land flat on the middle of the boat, but if you let the nose hit first it does seem to work.

Karma rear view
Another issue I have with planing hulls is that they can be grabby. The water will grab and turn you when you don't expect it. For the most part this didn't happen with the Karma. I never felt the stern get grabbed. But I did feel the bow catch. Not that it was a surprise - I often use holes and micro-eddies to help redirect my boat. Stick your nose in at an angle and let the water move you. With the Karma I was just getting turned a lot more than I expected. Again, it's something that will take getting used to. After several hours in the boat I was doing much better and managed to let the bow lead me through some quick slalom moves.

That's another area where the planing hull shines. A wave is not the only way to get the boat to plane. If you're traveling fast downstream and skim into an eddy where the current is moving up stream, the relative speed of the boat to the water can be enough for a quick burst of planing (0:54 in video). This can give you great control and speed when going through different currents, common when dodging around rocks. This was one of the funnest aspects of the Karma for me that I hadn't really found in class II/III water. It takes class IV boulder fields and some bigger, pushier water to really make the boat shine.

And our river got more gorged up and pushier as the day moved along. I found the firmer edge on the Karma made it easier to control in the big waves and made it easier to use the river to move where I wanted to go (2:18 in video). And as long as I kept my speed up I flew over the holes (1:55 in video). The only issue I had was on a seal launch where I wasn't paying attention and slid into a hole sideways without much speed - got flipped real quick. Definitely user error, but I do think my Villain would have been a little more forgiving. Just means I need to pay attention more.

By the end of the day I didn't feel like I had mastered the Karma, but I had a better understanding of it. And while I still think that the Villain (displacement hull) is the kind of boat that suits me and my paddling, I ordered myself a Karma. Having to figure out a new boat is a challenge and challenges can be fun. It's new and different and that can be scary, but if we don't push ourselves we don't learn and improve. I think the Karma gives me the benefits of the planing hull but in a way that is more forgiving than some of the boats I've tried in the past. Our creeking season is almost over here in California, but I should have a long summer of teaching and a few opportunities to push the boat on harder stuff. A good chance to learn and have it dialed when the winter rains and next spring's thaw roll around.


  1. Good description of the impacts of hull shapes. Thanks for that.

  2. So how would you compare the Karma to your Rocker? I'm considering making the switch from my MegaRocker to a Karma L.

    1. The Rocker is a very different boat. It's so round - I really liked it for some things but it had some drawbacks. On really shallow runs it slid over everything and it just laughed off cross currents. But it was hard to correct if you got off line and was hard to surf out of a hole if you did get stuck. The Villain has the positives of the Rocker without the drawbacks. The Karma is quite different.

  3. I was a Villain guy (both sizes) for 3 seasons who just swithced over to a med Karma. I agree with all you mentioned but would like to add one other thing that I found with the Karma: Seat Position. Unlike the Villain, the Karma's sweet spot became apparent when I moved my seat all the way back. Before that I was having a hard time getting the bow up on some moves as the Karma's full length edges really dictate how the boat performs while the Karma's huge boxy stern makes up for eveything else. Worth trying if you havnt already. Thx

    1. I haven't played with the seat position but I plan to. I've been using it in the middle position and it feels fine - but I do expect that the big back end will be able to handle a little more weight and moving the seat back might free up the nose a bit. Thanks.

  4. Fantastic write up Bryant, thanks for sharing this. I just found your post after getting my but kicked on my new Karma's virgin run down Cherry Creek last weekend. I'm trying to figure out what I can do to understand how it behaves, and this was the exact write-up I needed to see. Great breakdown on hull types, and how that specifically applies to the Karma. (Glad to see I'm not alone in my questions about it.)

    Just as you wrote, I found that my timing was off all day; the speed and lack of tracking surprised me. I felt like I was on a slip and slide, paddling up to boofs and eddy fences much higher than I had intended, or landing a boof only to be shot forward further than I expected. I was never quite sure how far the boat was going to travel or if it would hold it's line. Sometimes I would either ride up on a boulder above an eddy and spin out; other times I would back off at the last second but lose my momentum and miss the move. More than a few times the boat wouldn't engage across the eddy line enough, and I would simply blow past the eddy altogether. In short, I often didn't feel in control of the speed or angle of trajectory.

    And there were plenty of consequences. I manged to blow my line enough times to rack up a heavy toll with the river gods. I pulled my left oblique getting surfed in Unknown Soldier, broke my paddle in half in Ugly Stump, lost my GoPro off the front of the boat while swimming it to shore, and finally get broached at the very top of Horseshoe Falls, only to be dragged down over the rocks into the sticky hole at the bottom to be recirced several times while I fought to swim out of it.

    You know you've blown your line when:

    At the end of the day, I was beat. But all things considered, I'm thankful it wasn't worse!

    I'm hoping that you're right about just getting used to it. I do love the higher speed, the fact that it skips across holes, and that the stern compensated really well when I forgot to keep my weight forward. My strategy for the next trip is to take fewer (more purposeful) strokes and perhaps focus on keeping it more on edge in hopes of keeping the boat on track more.

    If you figure out anything else about your new boat, I'd love to see the update!